Chances of injuring the tympanic membrane with cotton bud are there but less with a self inflicted injury. Accidental push while cleaning ear mostly result in so. Most likely you must have injured the skin of the external auditory canal and bleeding is from there. Still, keep your ear dry, use cotton plug while taking bath, do not put any ear drops, and symptoms should go in few days with analgesics. Still if you are having severe pain or significant loss in hearing, do consult an ENT. Most small traumatic perforations heal without any treatment. regards